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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'e58b737cb43b4ea852a62eab36b1a3cf751f2a0a82ff44ddf6cfa4aa059f3096' 
  AND token = 'B8PagUlfZfrxdkq+CgkVabbgHHxw+RW6+aDInSdUBpA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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