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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6b4f8cbdcdb45a4ce47bebd3bd51bf54e7f6b0a0fc7a3f1c719bc758fef12696' 
  AND token = 'PUEjC37BNK2uS+vrgGoR90EP9XJddH1ostWieHZAqfY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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