SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'b97cdf999780362ebf2600ecc8552d6f9ed92b212d8a24ed2d51d62cf9d56802' 
  AND token = 'brEAGknAPoTLRoov206aIaghqAkiuuOJuvMldiU6c5w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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