SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '56caec8621bf4b250d85ea9d2f5932c92de37265640f4412e8f996b5048536a2' 
  AND token = 'mDgP8uJehDmM6iLh4wMketTSUJuzfMjgjcPt0/8g3Qw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}