SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b8c8ef6c49966edc96ab5e7b3dd9435a7f60e913dc6035baf751c708dcb10d48' 
  AND token = 'mXFAEZqVsvmcvkDwjVeJjz+8rK1hMPNEANt6YpaMY/U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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