SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a0a90acee574b09afbe0627066bac0a75f6e8462adba386870060216a4d6b5bd' 
  AND token = 'DQj/FSBJEMCnU4SxcuZnxtWbqurDihGGd7cL0Ny+iRU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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