SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '50b3b28313246f697b72ea184ebc31104f3b0e7f2c73e970570b20c8808bfe06' 
  AND token = '2w94bsAxQD6sakY8pIg3jYCwlaLGoK9T+biFGLOMvJs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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