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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '23f9438f4f82bfceff5e4b8b6abcd1ecf81b0a5267f232f09555da09c0da377c' 
  AND token = 'Uj/64ZeECUfXo5xtW8PTGCSW0WwAeHNNy+sT1iVfs7I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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