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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a81ce9d8f84f867261c93a6470503416da6445f6f4be0fe13ea4e7dc97f32275' 
  AND token = 'nWBcQZZnsAKiDvwMAYqdtowKxeLlyu13csSx6+/0Y68=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}