SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ec39a1816e60411c690143f0d9ef97b1e01de54a1f274787f66cb169692999c9' 
  AND token = 'ldcau3IfBGBr2YeTWgph4JNxNAHcC4UTYrAOkRt1EAg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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