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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fc8ce6239fd66210fdec86afb8894458bdabc8cc63e102f6f2a7644c6f3b4e8b' 
  AND token = 'ZCLAb3xRRsChWN31TgoLt5oyDnLV6W6LxLp+Di6ApXQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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