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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b4c9a2b090017aee13cb50f4be8aeb6edc2af4160e5c05b00d48f54867bc6dac' 
  AND token = 'CNnH0dZbcvdjhuGGtw0YeZyVsvJsNkDNNSQjIGPkJMs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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