SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '028f74bdd3b922f311d6943cf6307628c042139ad44658e57c796768a09bccaa' 
  AND token = '4p0Cvd6gu/jlgCARCYQ+dtYlJI02hQDCyrkMfxAVQvI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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