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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3f5109ebd5b104a32984e5c47acf2f8a3cf417d8b59fe708be5234c89a9e59b0' 
  AND token = 'qQ5ZXOfmnM3o0QrhnkhYDCJR3oRKs5XaN3Vn4n4kvCE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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