SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b8c61916b737ce35e7f1a13acba48ec5dc5fd623bd0505f48183778781987263' 
  AND token = 'WBT70b5UZvZcpj1Kb3AGm/pGDFCuhywrodFx9hZKsuE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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