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SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '7e78dcda506995142aeecdb174ab51140ff7942cc599b8c828d59976cd8ad90a' 
  AND token = 'M/FehD4/ltiLJiwX5DY8Eb2nUPzj00cajAS8JrmReZQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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