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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '73ed366f2ac27b0cbdef79a63382911d0fa404337f357301c6078205d38abafe' 
  AND token = 'cEY9jmXfclIYOlldvGQYgKmP0saCMBNTPoTe4dZUPow=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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