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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a8dffdf155690890e584bc4a52a7d8ee42655654fc58e7e191fe0ef55e4f9d01' 
  AND token = '0hlvfj+cpodsQTNLJNeF1XgPlDv2Lo0iwDQUIDf6M5I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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