SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'afabdef34800deb78cdd5443acd0643c1e59a1c0e673bbc8362ea3055b07f6a2' 
  AND token = 'F5v8XD9eubBWQhxUHMhvDWDZ+8w7CtOfy5pALrat188=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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