SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2b1bb54d729c69f68512fa13ca535520dc8cdf4373b66483fa5f4444b7f047ae' 
  AND token = 'zRmCCPgp6oo8nbvQL2DxZFfcQw1uDSCSfy3DtKNH6BE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}