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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3ebf7e7330561da8e3e5f0efcf1a7f9dc45cda3d6e28c67cf9d02c068d908f7e' 
  AND token = 'LFU9f723/1LLN/yhdWAKjIRmTptnWu1gdFzTuyF/MxI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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