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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a68fe8e410f0991d90bc1bbcd9ca9ce6c511d02e6a6b43b82f167bf6b3955d00' 
  AND token = 'c8ZyiLcjMFVvLRnXhXU7l/v3//ggB9r7otqc6JvAh5g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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