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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6f5017b1c483bf3d5c5cda0d2a82e712c0fda9fe6adb1d64771a9d6999a312f8' 
  AND token = 'ZuMn3d+a2aVgvTTurSbGFVhbMlfOOENp8zFPYcVVnqM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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