SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9853beb7f8f97c321df0b951349a18829e3df427188c0c9516aa3d8f0e3a1795' 
  AND token = 'RFOJCviliG9h7vzLN8jAgUVAb+A2Aed2iX6oZs/a5K8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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