SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b542100cdccb6ad610f420ac8645c2e8445378847609e2008b5f24ae2b970bed' 
  AND token = 'zfLlDwChXqhWZeeW23w21Hs+N9auqsEKlAnHHEJ7mUo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00053

JSON explain

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