SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c4152dcc0fa103eb10d070f2516eb148457c553daf5c056a22f2f7584d2ee703' 
  AND token = 'x1oGGhaxwITPxbAD4RNu2So1VeMBfaHLRmDCtUSziI0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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