SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5c8bf7d2be071590f8aca0c1c4a05e546be31668afdde88c52e47ac3f5435632' 
  AND token = 'OLjFnHRo2UOUmf+2Ai/wwKcH+mjJW52qPhQmW12J5PQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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