SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd2f562123ed7d6aab756be3c8609fe96838faab2f3a6944516feacda8af959d8' 
  AND token = 'WhYt5D2pdIaYY9x3b3Z1QtUW2HO+aleVuh6fetqaaG4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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