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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4e98efc81374091a5949c3842c601e7cc15a3e6b65c8d20acc65efaff0316db5' 
  AND token = 'oNQuYg7aMej/T+AwdUtOEFT5HafMMROwq21cDnMQo3g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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