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SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '63ce19b1f7c138c7032db678054a2af851859f7e7b93bf3844bf3df19af32e5e' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00049

JSON explain

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